Screw-threaded member



Sept R17, 1946. w. T. GooDBY 2,407,741

SCREWTHREADED MEMBER Filed' April 6,A 1944 1192A, magg. 11194. 16 '1W-' I6 2W.. r 0`". 3g

j .-179 Y 14C-v 1,421 I? w l .a

*W if 12 *"3* 26 V pg if' 5 'N 6 y 34'" y g] 10 1 101` l g3. Y 9 lImmzzr /Willzam Z 5ML@ vgrwyf 1 Patented Sept. 17, 1946 i PATENT OFFICE A SCREW-THREAD@ MEMBER William Thomas Goodby, Bristol, England; as-

signor-to-TheBristol Aeroplane Company Liam.- :ited Bristol, England, a British company ApplicationApril 6, 1944, Serial N0. 529,381?` Great BritainApril 2, 1943 This invention concerns screw-threaded'mem'- bers-of 'the type in wl-iiclruponA the male member being screwed into the female memberone of vsaid 7 ciaims. (o1. rs1-22') members lis forced linto intimate Contact with the other-"telcel:4 the members against separation.

According `to the present invention the male and l:female members are each Vso formed that upon-the male'mem'ber jbeing screwed into the female menfiber they coact to displacethe mate rial Aof 4the female mem-berend producea collar whose diameter rrris less than thev crest diameter invention the male member 'is screw-threaded over part of its length and is formed over another part of itsA length with'an unthreaded portion whose diameter lies-between the crest and trough diameters ofY the screw-thread, the arrangement vbeing that upon said member being screwed into the female membersaid'unthreaded portion engages the threads of the female member'thereby displacing them to form a locking collar which prevents separation of the two members;Y

AccordingV to yet another feature of 'the Vinventio-n the vmale vmember is formedwith a shoulder against which the material of the female member is'adapted to be forcedwhilst sai'collar is being produced. l

A `speciie embodiment of the present' invention asapplied to the holding-down studs for lajunkhead'oi asleeve-valve internalcombustion engine will now be described merely by way of example with reference to the accompanying drawing of which:

Figure l is a sectional elevation of a cylinder and junk-head assembly in which *thelatter is secured to the former by'ho-lding-down studs in accordance with the p-resentinvention;

Figure 2 'is an enlargedview of a blank "from which the holding-down studs are produced,

Figure 3 shows a holding-down stud which has been produced from saidblank,

Figure 4 is a sectional elevation ofY a studho'le which is adapted to 'receive the holding-down stud shown in 'Figure 3;

Figure 5 is asectional elevation oi a stud hole with a stud partly inserted therein, and

Figure 6 is a 'section on the lines'VI-VI of Figure l, this gure being to an enlarged scale foi the sake of clarity.

Referring to the drawing; the 'cylinder l0 of the internal combustion engine receives a plunuts |41 carried `on the studs Il.

rality-of spaced studs Il, said studs protruding from the end face of the cylinder and passing through a corresponding number of holes in the holding-down flange l2of the junk-head 13; The flangeof the junk-head is clamped into-intimate Contact with the end of the cylinder by It is .a common practiceyto provide an interference iit between the stu-ds H and their associated stud. holes l5 with `a view to ensuring that the studs do notwork loose during operation of the engine.` Thepresent invention aims at providing an improved form of lock for sai'dstuds.

According to the present invention'each `stud ll is formed with a locating collar i6 which separates that portion Il of they stud' which is screwed into the cylinder from the portion IB which protrudesthereirom to `receive the holding-down nuts I. The threads on the stud are formed by a thread-rolling operation in'which a blank I9 (Figure 2) whose shank diameter :r is

` approximately equal to the effective diameteroi stance at Eil) as otherwise there is a danger that the forming. rollers will come into engagement with the collar with consequent damage to said rollers since the collar has a greater ldiameter w than the shank of blank I9.

The stud which is produced from the blank-*I9 by the thread-rolling operation described above is shownin Figure 3. It willbe noted that the part l'l of the stud which is to be screwed into the cylinder comprises a threaded portion 2l ,thelol eating collar'i whose diameter w is approximately equal to the crest diameter z of the ,threads and lying between the threadedY portion 2l and the Acollar-t I6 a plain `portion 22 whose diameter .r is equal to the eective diameter of `the screw-V threads. A The trough diameter of the threads is indicated at Vy, l

To accommodate this stud; the stud holes. l5 of the cylinder are each iorme'd'with a threaded portion 23 which is off greater length than the threaded portion 2l ofthe stud;` an unthreaded portion 2,4f`whose diameter is the same as the diameter ofthe `locating collar I vl but whose depth is approximately-one-flfththereof, and a recessed portion 15 whose diameter i's-slightl'y greater allori/ii stud is brought into engagement with the threads of the stud holeV (Figure 5). When; the stud is screwed Vinto the stud hole from this position, the unthreaded portion` 22 squeezes the crests of the female threads lying -above the eifective diam-1 eter into their troughs thereby to produce a. collar 25 whose diameter is the same as the diameter Vof the unthreaded portion. When theV stud hasr been completely inserted in the stud hole l5, the` collar It (as shown in Figure 6) fits tightly into the unthreaded'portion 24, which is the same diameter as said collar, and passing through the recess portion 25 protrudes above the end face of the cylinder to receive the junk-head. The material forming collar 26 is consolidated'when the locating collar I6 engages with andcompresses it in an axial direction. l It will thus be appreciated that with a stud and stud hole of the constructions described there is formedon the insertion of the stud a locking collar `2li of material which is in intimate` contact with the stud and whoseA diameter is greater than the trough diameter and less than the crest diameter of the-male threads. This locking collar renders it difficult to unscrew the stud from the stud hole and also prevents the stud from working 10QSB! v i A further advantage of this constructioni resides inthe ability to ensure thatV the height which the studs protrude from the cylinder issub'stantially constant. This is dueto the fact that the degree of formation of the locking collar is a functionfof the depthto which the stud has been inserted and to the fact that itsformatiOn will ineach case require the exertion of approximately the same torque. When the latter has reached apre-determined value it therefore follows that the stud has entered into a stud hole to a predetermined depth. .Although the invention has been described as applied to the holding-down studs for a junkhead of a sleeve-valve internal combustion engine it will be appreciated that the invention may be applied tomany forms of screw-thread joints. Thus the invention has application to studs for supercharger oasings, gear boxes, and the like and to threaded collets, pipe joints and sparkp'lugada'ptors.

In putting the invention into effect the material of the female member of the joint may be of a more readily deformable material than the material of the male member 'such as aluminium, aluminiumfalloy ory magnesium when the male member. is of steel. Alternatively it may be of, a similar material, for instance steel or cast-iron with a male member of steel. In the embodiment described above the cylinder is an aluminium a1- loy' whilst the stud is `of steel. s I claim:

`1.l A threaded coupling comprising a threaded male member or bolt, and a complementarily .threaded socket or female member providing an anchorage for said bolt, said bolt comprising a threaded shankat the leadingend of the bolt, a plain vportion adjoining said threadedshank, a 1oc'atingcollar above the plain portion and an attaching portion above the collar, the diameter of said plain'portion being approximatelyequal to the effective diameter of the threads of the shank 4 bolt and being substantially of a length equal to the combined lengths of the threaded shank and plain portion of the bolt whereby when the leading end f the bolt is screwed into said socket throughout the full length of said threaded shank, such leading endA of; the lbollfwill Istill be above the lovverv end of 'the' threaded socket and further rotation of the threaded bolt will cause the plain portion of the bolt to squeeze the crests of the socket threads lying above their effective diameter into their troughs.

A 2. A threadedcoupling comprising a threaded f male ,memberI or bolt, and a complementarily threaded socket or female member providing an anchorage for said bolt, said bolt comprising a threadedshank at thevleading end of vthe bolt,

` a plain portion adjoining said threaded shank, a

1 exceeding that of thediameter ofsaid plain-portion, Vsaid socket having a threaded portion of greater length than .thethreaded shank of the bolt 4and being substantially o f a length equal to the combined lengths of the threaded shank and plain portion ofthe bolt whereby when the leadirig `end ov thel boltV isV screwed into said socket throughout the full length of said threaded shank, suohleading end of the bolt will still be above the lower end of the threaded socket and further rotation of the threaded boit will cause tnepiairi portion ofthe bolt to squeeze the crestsof the socket threads lying. above their .effective diameter into their troughs, said socket having an unthreade'd portionradjoiningthe upper end of the threaded portion and being of greater diameter than said threaded portion to receive the lower end'portion of said locating collar.

3. A threaded coupling comprising a male member having a threaded portion, a locating collar and an unthreaded portion intermediate the threaded portion and the collar, said unthreaded portion being of a diameter substantially equal tothe effective threaded diameter, and asocket member having a complementarily tlfireadedV portion deeper than the` threaded portionoi the male member whereby when the male member is screwed home said Vunthreaded portion K will displace crests of threads lof said socket portion, said socket having a threaded portion of t member into the troughs thereof to form a locking collar around said unthreaded portion of the male member at'the'entry end of the socket member. l

4. A threaded'coupling comprising a threaded male member and a complementarily threaded female memberof greater axial length than the male member for which it provides an anchorage; the male member having an unthreaded portion whosediameter issubstantially equal to the Veffective diameter of'thethreads, a threaded portion disposed between Ysaid unthreaded portion andV the end of the vmaleinember which enters the female member and a looatingfcollar disposed on the other side of saidunthreaded portion from said threaded portion, said 'unthreaded portionr in jwhichft'he said locating collar.- on-Vthe male p member is formed to provide a shoulder adjacent said unthreaded portion against which the material of the female member is adapted to be forced whilst said locking collar is being produced.

6. A threaded coupling as claimed in claim 4 in which the said locating collar on the male member is formed to provide a shoulder adjacent said Unthreaded portion against which the material of the female member is adapted to be forced whilst said locking collar is being produced, and wherein the unthreaded portion of the male member lies between the threaded portion thereof and said shoulder.

7. A threaded coupling as claimed in claim 4 in which the female member is formed 0f a material which is more readily deformable than the material of the male member.

WILLIAM THOMAS GO-ODBY. 

